The present invention is in the field of cylinders and seal rings for pistons, which are used in combination in internal combustion engines, and more particularly pertains to the selection of the materials of such rings and cylinders which mate during operation.
As is well known, internal combustion engines are run under high speed and high load conditions, which are quite sever on piston seal rings and cylinders. In order to provide a high wear resistance to the cylinder or the seal ring so as to accommodate them to such conditions, it is known to coat such cylinders or seal rings with Ni or an alloy thereof containing SiC, or to use as the cylinder base metal Al or an alloy thereof containing Si. By using cylinders and seal rings coated as described, the service life of the internal combustion engine can be improved. The improved characteristics are due to the fact that SiC and Si have a high degree of hardness. The SiC particles contained in the Ni or Ni alloy coating member and the Si particles contained in the Al or Al alloy base member tends to project out from the surface as the cylinder or ring wears, and to form a hard sliding face relative to the opposite mating member. On the other hand, the surface portions containing neither SiC nor Si particles wear to form pores in which oil is retained. This prevents scuffing and provides a good wear resistance over a prolonged period even under poor lubricating conditions.